Thionyl bromide

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Thionyl bromide
Structure of the thionyl bromide molecule
3D model of a thionyl bromide molecule
Molecular arrangement in solid SOBr2 (note that this is dramatically different from the crystal structure of its chloride analogue)
IUPAC name
Thionyl bromide
Other names
Sulfur oxy dibromide
507-16-4 N
ChemSpider 61483 YesY
ECHA InfoCard 100.007.332
Jmol 3D model Interactive image
PubChem 68176
Molar mass 207.87 g/mol
Appearance colorless liquid
Density 2.688 g/mL, liquid
Melting point −52 °C (−62 °F; 221 K)
Boiling point 68 °C (154 °F; 341 K) at 40 mmHg
Solubility reacts in HBr, acetone, and alcohol
soluble in benzene, toluene, ether
trigonal pyramidal
Main hazards sensitive to water
source of bromine, HBr
Safety data sheet "External MSDS"
R-phrases R14 R20/21/22 R29[1] R34
S-phrases (S1/2) S8[1] S26 S30 S36/37/39 S45
Flash point Non-flammable
Related compounds
Related compounds
SOCl2, SeOCl2;

PBr3, Br2

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Thionyl bromide is the chemical compound SOBr2. It is less stable and less widely used than its chloride analogue, thionyl chloride. It is prepared by the action of hydrogen bromide on thionyl chloride, a characteristic reaction where a stronger acid is converted to a weaker acid:

SOCl2 + 2HBr → SOBr2 + 2HCl

Thionyl bromide is used for some brominations of certain α,β-unsaturated carbonyls, and it also converts alcohols to alkyl bromides. Otherwise it hydrolyzes readily to release sulfur dioxide:

SOBr2 + H2O → SO2 + 2HBr


SOBr2 hydrolyzes readily to release dangerous HBr and acts as a lachrymator.


Mundy, B. P. (2004). "Thionyl Bromide". In Paquette, E. Encyclopedia of Reagents for Organic Synthesis. New York: J. Wiley & Sons. doi:10.1002/047084289X.rt098.